Alternative methods to analyse the impact of HIV mutations on virological response to antiviral therapy

Background  

Principal component analysis (PCA) and partial least square (PLS) regression may be useful to summarize the HIV genotypic information. Without pre-selection each mutation presented in at least one patient is considered with a different weight. We compared these two strategies with the construction of a usual genotypic score.     

High selectivity of the i f channel to Na+ and K+ in rabbit isolated sinoatrial node cells

The ionic selectivity of the hyperpolarizationactivated inward current (i _f) channel to monovalent cations was investigated in single isolated sinoatrial node cells of the rabbit using the whole-cell patch-clamp technique. With a 140 mM K⁺ pipette, replacement of 90% external Na⁺ by Li⁺ caused a –24.5 mV shift of the fully activated current/voltage I/V curve without a significant decrease of the slope conductance. With a 140 mM Cs⁺ pipette, the i _f current decreased almost proportionally to the decrease in external [Na⁺]_o as Li⁺ was substituted. These responses are practically the same as those observed with N-methyl glucamine (NMG⁺) substitution, suggesting that the relative permeability of Li⁺ compared with Na⁺ for the i _f channel is as low as that of NMG⁺. When Cs⁺ or Rb⁺ was substituted for internal K⁺, the fully activated I/V relationship for i _f showed strong inward rectification with a positive reversal potential, indicating low permeability of the i _f channel for Cs⁺ and Rb⁺. These results show that the i _f channel is highly selective for Na⁺ and K⁺ and will not pass the similar ions Li⁺ and Rb⁺. Such a high degree of selectivity is unique and may imply that the structure of the i _f channel differs greatly from that of other Na⁺ and K⁺ conducting channels.     

Lack of protection in mice and necrotizing bronchointerstitial pneumonia with bronchiolitis in guinea pigs immunized with vaccines directed against the hsp60 molecule of Mycobacterium tuberculosis

In this study, the hsp60 and hsp70 heat shock protein antigens of Mycobacterium tuberculosis were tested as potential vaccine candidates, using purified recombinant protein antigens or antigens encoded in the form of a DNA plasmid vaccine. Guinea pigs vaccinated with a mixture of the two proteins showed no evidence of resistance to low-dose aerosol challenge infection and quickly developed severe lung damage characterized by necrotizing bronchointerstitial pneumonia and bronchiolitis. As a result, we turned instead to a DNA vaccination approach using a plasmid encoding the hsp60 antigen of M. tuberculosis. Although immunogenic in mice, vaccination with plasmid DNA encoding hsp60 was not protective in that model or in the guinea pig model and again gave rise to similar severe lung damage. This study seriously questions the safety of vaccines against tuberculosis that target highly conserved heat shock proteins.     

An engineered biopolymer prevents mucositis induced by 5-fluorouracil in hamsters

Oral mucositis is a common, treatment-limiting, and costly side effect of cancer treatments whose biological underpinnings remain poorly understood. In this study, mucositis induced in hamsters by 5-fluorouracil (5-FU) was observed after cheek-pouch scarifications, with and without administration of RGTA (RG1503), a polymer engineered to mimic the protective effects of heparan sulfate. RG1503 had no effects on 5-FU-induced decreases in body weight, blood cell counts, or cheek-pouch and jejunum epithelium proliferation rates, suggesting absence of interference with the cytotoxic effects of 5-FU. Extensive mucositis occurred in all of the untreated animals, and consisted of severe damage to cheek pouch tissues (epithelium, underlying connective tissue, and muscle bundles). Only half of the RG1503-treated animals had mucositis, over a mean area 70% smaller than in the untreated animals. Basement membranes were almost completely destroyed in the untreated group but was preserved in the RG1503 group. RG1503 blunted or abolished the following 5-FU-induced effects: increases in matrix metalloproteinase (MMP)-2, MMP-9, and plasmin, and decreases in tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. These data indicate that mucositis lesions are related to massive release of proteolytic enzymes and are improved by RG1503 treatment, this effect being ascribable in part to restoration of the MMP-TIMP balance. RG1503 given with cancer treatment might protect patients from mucositis.     

Variable Regions 1 and 2 (VR1 and VR2) in JSRV gag Are Not Responsible for the Endogenous JSRV Particle Release Defect

Jaagsiekte sheep retrovirus (JSRV) is a betaretrovirus causing ovine pulmonary adenocarcinoma, a transmissible lung tumor of sheep. A very closely related endogenous retrovirus (enJSRV) occurs as 15 to 20 copies in the genome of all sheep, and is not known to be linked to pathogenesis. We previously localized a particle release defect of the full-length endogenous-derived expression construct pCMV2enJS56A1 to the amino-terminal region of gag that incorporates the two variable regions VR1 and VR2, which harbor the main sequence differences between endogenous and exogenous JSRV in this part of gag. Here, we tested the hypothesis that either or both of these variable regions are responsible for the observed particle release defect in enJS56A1. We found that the PPPPPPPS motif of the exogenous VR1 is neither necessary nor sufficient for particle release. Furthermore, the precise substitution of VR1 and VR2 in the exogenous JSRV expression plasmid pCMV2JS ₂₁, using their enJS56A1-derived counterparts, did not abrogate the ability of the resulting constructs to release particles. The particle release defect of enJS56A1 is therefore not determined exclusively by either VR1 or VR2. These results point to a small number of amino acids lying outside of VR1 and VR2 that may be responsible for the particle defect of enJS56A1 Gag.     

Adrenocortical adenoma and carcinoma: histopathological and molecular comparative analysis.

We compared histomorphological features and molecular expression profiles of adrenocortical adenomas (ACAd) and carcinomas (ACCa). A critical histopathological review (mean, 11 slides per patient) was conducted of 37 ACAd and 67 ACCa. Paraffin-embedded tissue cores of ACAd (n = 33) and ACCa (n = 38) were arrayed in triplicate on tissue microarrays. Expression profiles of p53, mdm-2, p21, Bcl-2, cyclin D1, p27, and Ki-67 were investigated by immunohistochemistry and correlated with histopathology and patient outcome using standard statistical methodology. Median follow-up period was 5 years. Tumor necrosis, atypical mitoses, and >1 mitosis per 50 high-power fields were factors that were highly specific for ACCa (P <.001). Number (0 to 4) of unfavorable markers [Ki-67 (+), p21 (+), p27 (+), mdm-2(-)] expressed was significantly associated with mitotic activity and morphologic index (i.e., number of adverse morphologic features) and highly predictive of malignancy (P <.001). Ki-67 overexpression occurred in 0 ACAd and 36% ACCa (P <.001) and was significantly associated with mitotic rate and unfavorable morphologic index (P <.001). Tumor necrosis, atypical mitoses, >5 mitoses per 50 high-power fields, sinusoidal invasion, histologic index of >5, and presence of more than two unfavorable molecular markers were associated significantly with metastasis in ACCa. Well-established histopathologic criteria and Ki-67 can specifically distinguish ACCAd from ACCa. Tumor cell proliferation (Ki-67) correlates with mitotic activity and morphologic index. Tumor morphology is a better predictor of metastatic risk in ACCa than current immunohistochemistry-detected cell cycle regulatory and proliferation-associated proteins.     

A patient with testis seminoma, sarcoidosis, and neutropenic enterocolitis

Seminoma and sarcoidosis do not seem to be associated diseases, judging from epidemiologic data. The presence of these two diseases in the patient whose case is reported may have been coincidental. It was observed, however, that when the testis tumor appeared in this patient, the longstanding sarcoid lesions significantly increased. The patient developed neutropenic enterocolitis after chemotherapy for a non-hematologic malignancy.     

Hepatitis B vaccine: further studies in children with previously acquired hepatitis B surface antigenemia.

Three doses of inactivated hepatitis B vaccine were given at 1-month intervals to 31 hepatitis B surface antigen (HBsAg)-positive Senegalese children aged between 3 and 24 months. A control group of 18 HBsAg-positive Senegalese children received diphtheria-tetanus-polio vaccine. Immunization of HBsAg-positive infants with hepatitis B vaccine was safe but inefficient. After a 12-month follow-up, the prevalence of HBsAg chronic carriers was not significantly reduced in the hepatitis B vaccine group as compared with the control group: 48.4 and 66.7%, respectively. The presence of hepatitis B antigen was found to be a major risk factor for HBsAg-positive children to develop a chronic carrier state. The risk of developing an HBsAg chronic carrier state was also related to advancing age at time of enrollment in the study.